Prediction of Physical Properties of Hydrocarbons, Petroleum, and Coal Liquid Fractions

Abstract

A simple method that uses the molecular structure and density as input parameters for the prediction of the normal boiling point (Tb), critical temperature (Tc), and critical pressure (Pc) of pure hydrocarbons is presented. For Tb the average absolute error is 1.0% as compared to 3.3% for the Joback method and 2.9% for that of Stein and Brown. Its main advantage over the first method lies with large molecular weight compounds and that over the second with highly branched compounds. For the prediction of Tc, the average absolute error is 1% similar to that of the Joback, Riazi, and Riazi−Daubert methods which, however, require knowledge of Tb. Finally, for Pc, the proposed method gives an average absolute error of 2.7% as compared to 3.9% for the Joback method and 4.2% and 4.8% for the Tb-requiring methods of Riazi and Riazi−Daubert, respectively. The proposed method gives also better results for these three properties when compared to the recently proposed and more difficult to use group interaction contribution method of Marejon and Fontevila. Using data for pure hydrocarbons, correlations have been developed for the prediction of molecular weight (MW), Tc, and Pc of petroleum and coal liquid fractions. MW prediction gives an average absolute error of 4.1% as compared to 4.6% for the Riazi−Daubert method, and both methods provide better results for coal liquids than the Starling and “single-parameter” expressions. Tc and Pc predictions with errors of 1.2% and 5.5% are similar to those of the Riazi−Daubert method, but no conclusion can be reached about the reliability of these methods because of the small number of available data.